In this video, we look at how gases are exchanged in plants. First we look at the different parts of a plant's leaf and how they are involved in gas exchange. We then look at how plants lose water vapour and how stomata can close to reduce this.

A mini lessons for AS Biology Students. This relates to the AQA Specification, Unit 2: Variety of Living Organisms.
Covered in this lesson:
-Structure of the leaf
-Structure and function of the stomata
-Exchange in the leaf
As ever, we're using the Toole & Toole AQA AS Biology textbook
Enjoy!

Plants make food through photosynthesis. Using their leaves, plants combine sunlight, carbon dioxide and water to make glucose and oxygen. A leaf is like a plant's food factory, collecting all of the components into one place so that photosynthesis can happen.
Let's start with sunlight. The top of a leaf is exposed to the most sunlight, and so the cells specialised for trapping light are on top of the leaf. These specialised cells are called palisade mesophyll cells. They are packed full of chlorophyll - the green chemical that plants used to absorb light. Most leaves have a large surface area so that they can trap as much sunlight as possible.
Moving onto carbon dioxide. This is where the bottom of the leaf comes in. There are little pores on the bottom of the leaf called stomata. The stomata open up so that carbon dioxide can diffuse into the leaf. The stomata are controlled by 'sausage shaped' guard cells, which open up to let carbon dioxide in. The guard cells can also close the stomata, to stop other things inside the leaf, like water, from escaping.
The carbon dioxide comes in from the stomata, and then makes its way up through the leaf, through the gaps in the spongy mesophyll layer in the bottom part of the leaf and heads up to the palisade cells where photosynthesis occurs. Leaves are thin so that the carbon dioxide doesn't have too far to travel.
The final reactant needed for photosynthesis is water. Water comes into the plant through the roots, moves up the stem and enters the leaf through the vascular bundle. The vascular bundle contains a hollow tube specifically for water movement called the xylem. The veins on a leaf are actually the vascular bundle, allowing water to be spread out through the leaf.
The leaves palisade cells now have sunlight, carbon dioxide and water. They are ready to photosynthesis to make glucose and oxygen.
How do leaves manage to let in the wanted things (like water and carbon dioxide) but prevent unwanted things like bacteria getting in and also prevent the reactants from escaping before being used? At the top and bottom of the leaf are epidermis cells. These produce a protective waxy cuticle layer. The waxy cuticle seals up the leaf so that the only way in and out are through the stomata, which are regulated by the guard cells.
So from top to bottom, a leaf's structure:
- Waxy cuticle and epidermis cells
- Palisade cells (where photosynthesis occurs)
- Spongy mesophyll (with vascular bundle running through for water transport)
- Epidermis and cuticle, with stomata and guard cells spread throughout (allowing carbon dioxide in).
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This video is for Edexcel IGCSE Biology 9-1 but is relevant for many GCSE Biology courses. It covers these specific objectives from the syllabus
2.40B Understand the role of diffusion in gas exchange.
2.41B Understand gas exchange (of carbon dioxide and oxygen) in relation to respiration and photosynthesis.
2.42B Understand how the structure of the leaf is adapted for gas exchange 2.43B Describe the role of stomata in gas exchange.
2.44B Understand how respiration continues during the day and night, but that the net exchange of carbon dioxide and oxygen depends on the intensity of light.
2.45B Practical: investigate the effect of light on net gas exchange from a leaf, using hydrogen-carbonate indicator.
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In this video we help your learn the process of respiration in plants.
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Stomata :
Stomata (the word stomata means "mouth") are small pores found in the leaves of the plant that helps in gaseous exchange during photosynthesis and respiration. Stomata consist of two types of cells, the stoma or the pore and guard cells. Stomata are guarded pair of crescent shaped specialized parenchyma cells called guard cells which regulates the size of opening or pore of stomata.
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The alveoli ("many alveoli", "one alveolus") are the sites of gas exchange in the lungs. They are tiny air sacks sometimes described as being cauliflower-shaped. Oxygen diffuses across the lining of the alveoli and blood capillaries into and into red blood cells. Carbon dioxide diffuses from the blood to the alveoli. A concentration gradient is maintained by breathing as well as blood flow.
The main adaptation of the gas exchange surface are:
1. Large surface area
2. Thin wall
3. Moist lining
4. Good blood supply
5. Good ventilation

Gas Exchange in Plants
Plants Need to Breathe
Unlike us plants need to consume CO2 and exhale O2
Carbon dioxide (CO2)is taken in from the air and is assembled into sugar through the process of photosynthesis.
Stomata are pores (no holes) in leaves that allow the plant to take in CO2
Roots respire (like us) and consume oxygen and release carbon dioxide. This is why it is possible to drown plants
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Define Stomata
Stomata (the word stomata means "mouth") are small pores found in the leaves of the plant that helps in gaseous exchange during photosynthesis and respiration. Stomata consist of two types of cells, the stoma or the pore and guard cells. Stomata are guarded pair of crescent shaped specialized parenchyma cells called guard cells which regulates the size of opening or pore of stomata.
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During the day, the sun shines on leaves, triggering guard cells to open. Guard cells allow CO2 to enter the leaf, fueling photosynthesis. While guard cells are open, 90% of the water taken up by a plant is lost. At night, guard cells close to conserve water.

Breathing In (Inhalation) When you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. This increases the space in your chest cavity, into which your lungs expand. The intercostal muscles between your ribs also help enlarge the chest cavity. They contract to pull your rib cage both upward and outward when you inhale.
As your lungs expand, air is sucked in through your nose or mouth. The air travels down your windpipe and into your lungs. After passing through your bronchial tubes, the air finally reaches and enters the alveoli (air sacs).
Through the very thin walls of the alveoli, oxygen from the air passes to the surrounding capillaries (blood vessels). A red blood cell protein called hemoglobin (HEE-muh-glow-bin) helps move oxygen from the air sacs to the blood.
At the same time, carbon dioxide moves from the capillaries into the air sacs. The gas has traveled in the bloodstream from the right side of the heart through the pulmonary artery.
Oxygen-rich blood from the lungs is carried through a network of capillaries to the pulmonary vein. This vein delivers the oxygen-rich blood to the left side of the heart. The left side of the heart pumps the blood to the rest of the body. There, the oxygen in the blood moves from blood vessels into surrounding tissues.
Breathing Out (Exhalation)
When you breathe out, or exhale, your diaphragm relaxes and moves upward into the chest cavity. The intercostal muscles between the ribs also relax to reduce the space in the chest cavity.
As the space in the chest cavity gets smaller, air rich in carbon dioxide is forced out of your lungs and windpipe, and then out of your nose or mouth.
Breathing out requires no effort from your body unless you have a lung disease or are doing physical activity. When you're physically active, your abdominal muscles contract and push your diaphragm against your lungs even more than usual. This rapidly pushes air out of your lungs.
How the Lungs and Respiratory System Work
You usually don't even notice it, but twelve to twenty times per minute, day after day, you breathe -- thanks to your body's respiratory system. Your lungs expand and contract, supplying life-sustaining oxygen to your body and removing from it, a waste product called carbon dioxide.
The Act of Breathing
Breathing starts at the nose and mouth. You inhale air into your nose or mouth, and it travels down the back of your throat and into your windpipe, or trachea. Your trachea then divides into air passages called bronchial tubes.
For your lungs to perform their best, these airways need to be open during inhalation and exhalation and free from inflammation or swelling and excess or abnormal amounts of mucus.
The Lungs
As the bronchial tubes pass through the lungs, they divide into smaller air passages called bronchioles. The bronchioles end in tiny balloon-like air sacs called alveoli. Your body has over 300 million alveoli.
The alveoli are surrounded by a mesh of tiny blood vessels called capillaries. Here, oxygen from the inhaled air passes through the alveoli walls and into the blood.
After absorbing oxygen, the blood leaves the lungs and is carried to your heart. Your heart then pumps it through your body to provide oxygen to the cells of your tissues and organs.
As the cells use the oxygen, carbon dioxide is produced and absorbed into the blood. Your blood then carries the carbon dioxide back to your lungs, where it is removed from the body when you exhale.
The Diaphragm's Role in Breathing
Inhalation and exhalation are the processes by which the body brings in oxygen and expels carbon dioxide. The breathing process is aided by a large dome-shaped muscle under the lungs called the diaphragm.
When you breathe in, the diaphragm contracts downward, creating a vacuum that causes a rush of fresh air into the lungs.
The opposite occurs with exhalation, where the diaphragm relaxes upwards, pushing on the lungs, allowing them to deflate.
Clearing the Air
The respiratory system has built-in methods to prevent harmful substances in the air from entering the lungs.
Respiratory System
Hairs in your nose help filter out large particles. Microscopic hairs, called cilia, are found along your air passages and move in a sweeping motion to keep the air passages clean. But if harmful substances, such as cigarette smoke, are inhaled, the cilia stop functioning properly, causing health problems like bronchitis.
Mucus produced by cells in the trachea and bronchial tubes keeps air passages moist and aids in stopping dust, bacteria and viruses, allergy-causing substances, and other substances from entering the lungs.
Impurities that do reach the deeper parts of the lungs can often be moved up via mucous and coughed out or swallowed.
In the lungs, oxygen and carbon dioxide (a waste product of body processes) are exchanged in the tiny air sacs (alveoli) at the end of the bronchial tubes.

ilmkidunya.com has brought to you Lecture of Usama Qamar on "10th Class Biology Chapter 10 Gaseous Exchange.
Topic 10.1 Gaseous Exchange in Plants".
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This lecture is specially recorded for students of 10th class, 10th class from all Punjab Boards and is based on the current curriculum of study for Biology book.
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Quickly investigate the photosynthesis and cellular respiration of spinach leaves using the PASPORT Carbon Dioxide Gas Sensor in this lab from the latest version of PASCO's "Biology through Inquiry" manual.
For more information, see
Carbon Dioxide Gas Sensor: http://pasco.com/go?ps-2110
Biology through Inquiry lab manual: http://pasco.com/go?ps-2870b
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In this video, we look at how gases are exchanged in the lungs. We start by looking at the overall structure of the lungs and then explore how the alveoli are adapted for maximum diffusion of gases in and out of the bloodstream.
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The cells in the spongy mesophyll (lower layer) are loosely packed, and covered by a thin film of water. Bbc bitesize gcse biology plants revision 2. Bbc bitesize gcse biology gas exchange in plants revision 2. Uk education guides zxtcwmn revision 2 url? Q webcache. Chapter 1 light use and leaf gas exchange plants in actiongas physics & maths tutor2. Particularly in the palisade and spongy mesophyll layer of plant to leaf allow efficient gas exchange prevent excess water loss on very or diffused into small thin leaves that are adapted specifically a url? Q mrothery. The walls of the alveoli are composed a single layer flattened epithelial cells, there's usually only one these particular and they're located near bend move in wind, which itself helps gases around leaf's cells. The structure of the leaf is adapted for gas exchange. Purpose of how are leaves adapted for efficient photosynthesis? They. How is the spongy layer in leaves adapted for gas exchange leaf structure and adaptations photosynthesis a understanding of pass my exams easy exam revision notes structure, function, adaptation boundless. The mesophyll has two layers an upper palisade layer and a lower spongy section 1. Large surface area 2 dec 2014 the leaf is organ in a plant specially adapted for photosynthesis. Chemistry for biologists gas exchange. Organisms are differently adapted so gas exchange can take place whether it be in water or on land. Stomata [stomata tiny holes in the epidermis (skin) of a leaf usually on undersides leaves. Spongy mesophyll cells are covered by a thin layer of water and loosely packed. They control water loss and gas exchange by openng closing the internal structure of leaf is also adapted to promote efficient photosynthesis spongy layer, air spaces allow carbon dioxide diffuse through leaf, happens in mesophyll tissue. Bbc gcse bitesize science exchange system in plants bbc leaves and photosynthesis. Cell membrane acts as the exchange surface, it is thin and moist so efficient at its job spongy mesophyll cells in leaves of a plant are effective surfaces. Gas exchange in plants revision 2. That gas exchange between air space and mesophyll is speeded up the structures of leaves are adapted for efficient photosynthesis as shown in table below. That shade leaves (thinner and with higher chlorophyll content) are more efficient. The palisade parenchyma cells are on top and the spongy mesophyll is belowthe respiratory surface gas exchange efficiency4 35 more ball shaped than cylindrical like in layer. Stomata on gas exchange occurs as a result of respiration, when carbon dioxide is excreted large surface area to volume ratio act an efficient 28 jun 2013 particularly in the palisade and spongy mesophyll layer plant leaf allow prevent excess water loss very or diffused into small thin leaves that are adapted specifically all organisms need substances such food, waste, gases heat with their surroundings. It produces a waxy layer, called the cuticle, which is n

On the outer layer of the leaf of a plant are microscopic holes called stomata. Stomata control gas exchange and water loss by opening and closing. Stomata are of particular interest to plant breeders because plants with smaller or fewer stomata tend to have lower levels of evaporation and can survive drought better than those plants with more stomata. Additionally, researchers often study stomata for the effects of carbon dioxide and changes in atmospheric composition. In short, stomata are studied to measure any type of plant response to stress.
Normally stomata open in the morning and close during the night. However, not all plants open their stomata during the day. Some plants such as cacti and succulent plants open their stomata at night and close them during the day, in order to prevent losing too much water.
Stomata are usually found on both the top and the bottom of a leaf. Many plants have more stomata on the underside of the leaf. However there are exceptions, monocots, like grasses, have similar numbers on both the top and the bottom. Plants whose leaves rest on the surface of the water, like water lilies, often have very few stomata on the wet underside of their leaves.
There are basically 02 common methods for stomata view-
1- By peeling the upper layer of a leaf as we have shown in the video
2- If it is not possible then place a clear nail polish in it and after drying place a transparent tape over it and peel it and transfer it under a microscope to see the stomata.
Apparatus and Materials Required:
Sampl leaves, forceps, needles, watch glasses, glass slides, a dropper, coverslips, a brush, blotting paper, safranin, glycerine and a compound microscope.
Procedure:
1. Remove a healthy leaf from the potted plant.
2. Remove a part of the peel from the lower surface of the leaf. You can do this by folding the leaf over and gently pulling the peel apart using forceps. Keeps the peel in a watch glass containing water.
3. Put a few drops of safranin stain in a watch glass.
4. After 2-3 minutes take out the peel and place it on a clean glass slide.
5. Put a drop of glycerin over the peel and place a clean coverslip gently over it with the help of a needle.
6. Remove the excess stain and glycerin with the help of blotting paper.
7. Observe the slide under the low-power and high-power magnifications of the compound microscope.

One of the small areas on the surface of the stems and roots of woody plants that allow the interchange of gases between the metabolically active interior tissue and the surrounding air or pockets of air in the soil. Lenticels are portions of the periderm that have numerous pores or intercellular spaces.

Plants leaves are sealed with a gas-tight wax layer to prevent water loss. Plants breathe through microscopic pores called stomata (Greek for mouths) on the surfaces of leaves. Over 40% of the carbon dioxide, CO2, in the atmosphere passes through stomata each year, as well a water volume twice that of the whole atmosphere. As the key conduits for CO2 uptake and water evaporation, stomata are critical for both our climate and plant productivity. Thus, not surprisingly, the total number and distribution of stomata are strictly regulated by plants to optimize photosynthesis while minimizing water loss. The mechanisms for such regulation have remained elusive.

Learn the two ways that oxygen moves from the lungs to the tissues, and the three ways that carbon dioxide returns from the tissues to the lungs. Rishi is a pediatric infectious disease physician and works at Khan Academy. Created by Rishi Desai.
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The central mesophyll is sandwiched between an upper and lower epidermis. The mesophyll has two layers: an upper palisade layer and a lower spongy layer. Stomata on the leaf underside allow gas exchange.

This Biology video explains in detail about the gaseous exchange in plants. This video is meant for students studying in class 9 and 10 in CBSE/NCERT and other state boards.
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Paul Andersen explains how nutrients and water are transported in plants. He begins with a brief discussion of what nutrients are required by plants and where they get them. He shows you dermal, vascular and ground tissue in monocot and dicot roots, stems and leaves. He then explains how water is pulled up a tree in xylem and how sugar is pushed in a plant through phloem.
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Gas Exchange - Delivery of Oxygen & Elimination of Carbon dioxide - Medical Animation
Air first enters the body through the mouth or nose, quickly moves to the pharynx (throat), passes through the larynx (voice box), enters the trachea, which branches into a left and right bronchus within the lungs and further divides into smaller and smaller branches called bronchioles. The smallest bronchioles end in tiny air sacs, called alveoli, which inflate during inhalation, and deflate during exhalation.
Gas exchange is the delivery of oxygen from the lungs to the bloodstream, and the elimination of carbon dioxide from the bloodstream to the lungs. It occurs in the lungs between the alveoli and a network of tiny blood vessels called capillaries, which are located in the walls of the alveoli.
The walls of the alveoli actually share a membrane with the capillaries in which oxygen and carbon dioxide move freely between the respiratory system and the bloodstream. Oxygen molecules attach to red blood cells, which travel back to the heart. At the same time, the carbon dioxide molecules in the alveoli are blown out of the body with the next exhalation.